CMOS circuitry implemented on a standard bulk Si wafer rather than in a thin layer of active Si on insulator (SOI substrate).

wafer

thin (thickness depends on wafer diameter, but is less than 1 mm), circular slice of single-crystal semiconductor material used in manufacturing of semiconductor devices and integrated circuits; depending on material wafer diameter may range from about 25 mm to 300 mm; cut from the ingot of single crystal semiconductor.